I've got 158K miles on my original alternator. Might be because I have a low end model with only the basic power items. No power or heated seats, no ELC, no ECC, etc.
I would definitely consider the factors mentioned above:
- How often car is driven = battery drain
- What quality rebuilt Alternator is going into car = case of you get what you pay for
- Maybe put in 140A alt. = particularly if the first two aren't the issue and he has all the bells and whistles
Other than that, have a GOOD auto electrician (hard to find) test for intermittent shorts. I had an Olds Cierra that ate alternators for a year or so until I found a great electrician. He found an intermittent short in 5 minutes. Problem gone. I was so happy I tipped him.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s